(HealthDay News) -- A sprained thumb occurs when ligaments stretch beyond their limits. The most common cause of a sprained thumb is falling onto an outstretched hand, the American Academy of Orthopaedic Surgeons says.
Depending on the sprain's severity, you may have bruising, tenderness and swelling around the base of your thumb. Difficulty grasping things also is common.
For mild thumb sprains, the academy recommends the RICE protocol: